‘Mysterious opals contain the wonders of the skies – sparkling rainbows, fireworks, and lightning, shifting and moving in their depths.’
Opals have the power to display all the colours of the rainbow in an iridescent pattern, from blue, red and pink, to yellow, green, purple and any other hue.
But what are opals made of? What causes them to display a kaleidoscope of colour? Let Volle Jewellery, one of the leading opal Sydney jewellers, help you uncover the secrets of one of the most sought-after gemstones in world.
How Do Opals Get Their Colours?
Like butterflies and hummingbirds that get their colour when light hits their bodies, opals gain their ‘play of colour’ when a light ray encounters small obstacles or slits. When the light wave bends as it passes around the edge or through the small openings, the ray breaks apart and scatters the wave into visible rainbow hues. This phenomenon is known as diffraction. To understand how this happens, you need to learn the structure of opals.
The Structure of Opals
Opals consist of silica and water. When silica from the soil mixes with water, a silicate-rich solution is formed. This solution enters a cavity or is trapped in layers under the earth, forming different types of opals.
Over time, the silicate-rich solution settles and the water evaporates, forming layer upon layer of silica spheres. The layers of precipitated silica spheres turn into a jelly-like water mass, producing a diffraction grating when the spheres are even in sizes and well-ordered. This creates a ‘play of colour’ from within the stone when it is moved and the light hits the spheres in different angles.
The Size of the Spheres
The size of the spheres determine what colours or type of opals are produced. The more uniform are the spheres’ sizes, the more brilliant, defined and intense are the colours of the opals. Common opals are made when the spheres have random arrangement and shape. Precious opals are created when the spheres are regular in shape and size and there is an evident play of colour. Smaller spheres that are less than 150 nm bring out the blues and violets while larger spheres no longer than 350 nm produce reds and oranges in the opals.
Bottom Line
Opals vary in appearance and quality. These gems are not only mysterious, they are as unique and individual as your fingerprint. These characteristics are what make opals one of the most sought-after gemstones used to create timeless jewellery pieces.
Looking for exquisitely crafted opals, pearls and pink diamonds in Sydney? Visit us today.
Whether you’re looking for genuine Australian pink diamonds and pearls, or rare and captivating precious opals, Volle Jewellery’s stunning pieces are perfect as gifts for any occasion.